Hydrocarbon oil conversion



Nov. 6, 1934. N. G. DE RACHAT HYDROCARBON OIL CONVERSION Filed Jan. 26,1931 2 Sheets-Sheet 1 INVENTOR NICHOLAS C. DE RACHAT BY ATTORNE Nov. 6,1934- N. G. DE RACHAT HYDROCARBON OIL CONVERSION Filed Jan. 26, 1931 2Sheets-Sheet 2 FIG. 2

Patented Nov. 6, 1934 I PATENT OFFICE 1,979,532 HYDROGARBON on.CONVERSION Nicholas G. de Rachat, Chicago, 111., assignor to UniversalOil ProductsCompany, Chicago, 111., a corporation of South DakotaApplication January 26, 1931, Serial No. 511,139

' 3 Claims. (C1.-196-49) This invention relates to the treatment ofhydrocarbon oils and refers more particularly to the treatment ofcracked residues to produce coke-like particles therefrom. 4

5 More specifically, the invention contemplates the treatment of heavyliquid residues produced in processes employed for the conversion ofheavy hydrocarbon oils into lighter oils of lower boiling point range.These liquid residues, which are commonly of a pitchy or asphalticnature, and which may contain highly carbonaceous particles insuspension, may be subjected to heat, devolatilized and partiallyoxidized by contact with hot furnace gases, as will hereinafter bedescribed, In the production of maximum yields of low boilinghydrocarbons, cracking processes are frequently operated underconditions of tempera- 'ture and pressure of such proportions as toresult in relatively severe or' intensive cracking, with the-productionof only fixed gases and solid residues other than the desired lowboiling point gasoline fractions. When such operations are effected,great mechanical difficulties are encountered, due to the cokedeposition tending to plug or stop-the various lines and valves of thesystem, and its removal at intervals from settling drums is consequentlynecessary for continuous operation of such processes. The residues thusproduced are consequently ,of varying density, hardness and porosity,depending upon the conditions attending their formation and deposition,and are frequently only utilizable as a cheap grade of fuel. Forexample, the coke removed from the lower portion of a chamber may befound to be soft or hard, depending upon whether liquid charging oil waspresent in the chamber when the cracking plant was shut in andconversion conditions commenced. Succeedingstrata may also vary, due tocomparatively slight fluctuations in the temperature and pressureemployed, so that the total amount of coke removed from the chamber maybe of a'distinctly non-homogeneous character, varying from soft andeasily pulverizable portions which require special blowers for theireflicient combustion, to relatively hard lumps, re-

sembling coal, which must be separated from the 'softer material and.burned in separate equip ment.

In cracking plants not designed for crackingjo coke, the problem ofproducing maximum yields of gasoline with minimum production of cokepresents itself. Endeavors to attain this condition sometimes result inthe production of resi-' dues which contain appreciable amounts ofcarbonaceous or coke-like particles which render the liquid difficult touse in ordinary atomizing burners.

The present invention, therefore, is concerned with improved methods andmeans for the controllable production of finely divided carbon orcoke-like particles of a uniform and lamp blacklike character, with theattendant feature of increased production of gasoline fractions.

In one specific embodiment of the invention, heavy liquid residues-fromcracking operations may be discharged at a fixed rate onto atomizing umeans comprising rapidly revolving horizontal discs disposed on a shaftco-axially supported in a vertical cylindrical treating chamber, hotflue gases from the cracking furnace being introduced in concurrent flowwith the atomized liquid, the coke particles separated from theresultant gases in suitable settling space and the gaseous mixturestripped of its low boiling point hydrocarbon fractions after indirectheat exchange with incoming raw charging stock to the cracking process.

Other. and further objects and advantages of the invention will becomeapparent from thefollowing description and diagrammatic drawings, 30 inwhich,--

Fig. 1 is a side-elevational view of one form of apparatus in which theinvention may be carried out; and

Fig. 2 is a vertical, cross-sectional view of a form of coking apparatuswhich may be employed in the 'processs.

Referring to the drawings, heavy hydrocarbon oil to be cracked may bepassed via a line 1, controlled by a suitable valve 2, to a pump 3, anddischarged therefrom into a line 4, controlled by a valve 5, and passedthrough an indirect heat exchanger 8, wherein the oil may be preheatedby the gases passing therethrough in a. heated state from a cokingchamber to be hereinafter more particularly described, said oil, inturn, serving to cool said gases. The preheated oil may be passed fromsaid heat exchanger 8 through a line 9, controlled by a valve 10, into aline 6,

controlled by a valve 7. Said line 6 may comcombined in a line 11,controlled by a suitable valve 12, andmay be passed into a line,13,controlled by a valve 14 leading to a fractionator 29 of anyconventional type or combination of equipment adapted to effectseparation of cracked vapors into light and heavy portions, or into a noline 15', controlled by a valve 16, leading to a pump 1'7 discharginginto a line 18', controlled by a valve 19' into a heating element 20disposed within a suitable furnace 21, as desired. Insufiicientlyconverted intermediate portions from fractionator 29 may be withdrawntherefrom for retreatment, through a line 18, controlled by a valve 19,leading from the lower portion of said fractionator, and may communicatewith said line 15 leading to pump 17, so that a mixture of raw oil and.relatively heavy, insufficiently convertedfractions may be introducedinto the conversion zone or heating element 20.

After passage through heating element 20, wherein suflicient heat andpressure may be maintained to promote conversion of the oil passingtherethrough, the heated products may pass through a line 22, controlledby a valve 23, to an enlarged chamber 24, of any conventional type,where further reaction may occur. Vapors from said reaction chamber maythen pass through a line 27, controlled by a valve .28, to said frac-'tionator 29.

Unvaporized liquids from reaction chamber 24 may be released through aline 25, controlled by a valve 26 and a valve 26, for discharge into acoking chamber 40, insulated, preferably, by any suitable material, asat 40' in order .to maintain relatively high temperatures during thecoking period and prevent a consequent severe heat loss. Within chamber40 may be suitably disposed a plurality of discs 47, integrally mountedon a powered shaft 46 disposed substantially throughout the centralportion of said chamber, and adapted to rotate through communicationwith any desired motivating means 45 disposed in the upper part of saidchamber. The lower portion of said shaft 46 may be suitably disposedwithin a bearing member 50. A plurality of cones 48 may be also disposedwithin said chamber 40, so as to efiectively'direct partially treatedmaterials back to the center of the chamber for further atomizationthrough contact with succeeding discs disposed at lower levelsthroughout said chamber.

As an additional feature of the invention, flue gases, preferably fromthe cracking furnace, may be introduced through a line 41, controlled bya valve 42, intothe upper section 43 of said chamber 40, separated fromthe main coking chamber by means of a perforated plate 44, the latterplate serving to evenly direct and distribute the gases in theirdownward flow through said chamber. Liquid materials on entering .saidchamber 40 through said line 25, fall upon the discs 47. and

are thrown violently, due to the centrifugal action point, with theresultant formation of coke par- .ticles of any degree of subdivision.

The gases and solids from the final or lowest atomizing zone may passinto a space 51, divided by a cone 51', where final'separation of solidcarbonaceous particles and gases may occur, the

separated gases being withdrawn through a line 52.- In order to efi'ectcontinuous removal of settled solids in the lower part of said chamber40, an exit line 59 may be provided, within which may be disposed asuitable screw 58, actuated by powered gears 60, through any desiredsource of power (not shown) By proper manipulation of the screw 58, aslight level may be maintained in chamber 40, and exit line 59 which mayeffectively seal the bottom of said chamber and prevent the escape ofvapors therefrom.

It will be evident from the foregoing description of the coking chamber,that it is adapted to produce coke particles of a size and quality whichmay vary over a wide range. By the use of large amounts of flue gas andrapidly revolving discs and the resultant fine atomization, lamp blackmay be produced, and, with less severe conditions, a uniform grade ofcoke particles adapted to be burned as breeze coke may be obtained.

. The gaseous mixtures leaving through line 52 may contain substantialquantities of low boiling hydrocarbon fractions, and may pass through avalve 53 to heat exchanger 8 wherein they may flow countercurrent to theflow of oil charge to the cracking process, as previously described.Such portions of the gaseous mixture passing through said heat exchangeras may condense due to cooling by heat exchange with the charging oilflowing therethrough, may be withdrawn from said heat exchanger througha line 56, controlled by a valve 57 and passed to a receiver 70, to behereinafter more fully referred to; and the gaseous portions stillremaining in said heat exchanger may be withdrawn therefrom through aline 54, controlled by a valve 55, and pass into a line 61, controlledby a valve 62, leading to an absorption tower 63 of any conventionaltype. A suitable cooling and absorbing media may be introduced into saidabsorption tower 63 through a line 64, controlled by a valve 65.Stripped gases may be withdrawn from said absorption tower througha-line 66, controlled by a valve 6'7, and passed to storage. whileabsorption liquids containing substantial amounts of gasolinehydrocarbons may be withdrawn from, said tower through a line 68,controlled by a suitable valve 69 to a receiver 70. Receiver 70 may beprovided with a line 71, controlled by a valve .72, through which fixedgases may be removed, as well as a line '73, controlled by a valve '74for the eduction of liquids for redistillation in subsequent equipment(not shown) of the process.

Vapors from fractionator 29 may pass through a line 30, controlled by asuitable valve 31, into a condenser 32, wherein cooling is effected, thecooled and partially liquefied products issuing from said condenserthence passing through a line '33, controlled by a valve 34, into areceiver 35. Uncondensed vapors and gases may be withdrawn from saidreceiver 35 through a line 36, controlled by a valve 37, and introducedinto absorbing tower 63 via line 61 in communication with line 36.Liquid products, containing substantial quantities of gasoline boilingpoint hydrocarbons may be removed from receiver 35 through a line 38,controlled by a valve 39, and passed via said line to run-down line 73issuing from receiver '70, effecting a combining of the products fromreceiver 35 and 70, so that gasoline fractions from the cracking andcoking processes may be recovered simultaneously in the subsequentdistillation process.

Conversion temperatuiesemployed may range from about 750 to 1050 F.,more or less, while pressures employed may preferably be of substantialsuperatmospheric order, although atmospheric, or even sub-atmosphericpressures may be employed, as desired, depending upon the nature of thecharging stock under treatment.

As one example of the results obtainable by an adaptation of theprinciples of the present invention, a 25 gravity topped crude,characteristic of the Mid-Continent producing area, was

cracked to produce approximately 55% of hydrocarbons of gasoline boilingpoint,'and about 35% of heavy residual liquids of a nature bordering onextremely heavy asphalt, which must be maintained in a relatively highlyheated condition in order to keep it fluid. This residue was dischargedinto a coking apparatus substantially similar'to that described andtreated by the process of my invention, with a resultant produc-' tionof finely divided breeze coke equal to apthrough a heating zone andheating the same i therein to cracking temperature under pressure,introducing the hot oil stream to a reaction zone maintained undercracking conditions of temperature and pressure, continuously removingvapors and unvaporized oil while still hot to a coking zone andimpinging the same against a rapidly rotating surface therein to impartcentrifugal velocity to the unvaporized oil, introducing to the cokingzone highly heated gases of sufficient temperature to coke theunvaporized oil,

contacting the gases with the unvaporized oil in the coking zone anddistilling the unvaporized oil to coke therein, and removing the. cokeand the vapors and gases from the coking zone.

2, The process as defined by claim 1 further characterized in that theunvaporized oil is passed in a generally downward direction through thecoking zone and, during its downward movement therethrough, successivelydeposited upon additional rotating surfaces at intervals in the path ofdownward movement.

3. The process as defined by claim 1 further characterized in that theunvaporized oil is passed in a generally downward direction through thecoking zone and, during its downward movement therethrough, successivelydeposited upon additional rotating surfaces at intervals in the path ofdownward movement, the process being still further characterized in thatsaid highly heated gases are passed downwardly through the coking zoneconcurrently with the unvaporized oil.-

, NICHOLAS G. DE RACHAT.

